Preparation Of Novel Cationic Water-Soluble Conjugated Polymers And Their Application In Cell Imaging And Gene Delivery

As an emerging revolutionary therapy,gene therapy has always received much attention.However,effective gene therapy relies heavily on whether the gene delivery system can successfully introduce exogenous genes into recipient cells.Therefore,the development of safe and efficient delivery vectors for gene therapy is urgently needed in gene therapy research.At present,the vectors for gene delivery mainly include viral vectors and non-viral vectors.Although the viral vector has high transfection efficiency,the defect of its genetic mutation risk limits its further clinical application as gene delivery vector.Among non-viral vectors,polymer carriers have become one of the hotspots of research because of their biosafety and high transfection efficiency.As a new type of optoelectronic polymer materials,due to its good biocompatibility and excellent fluorescent properties,water-soluble conjugated polymers can also track the gene delivery process through real-time imaging while carrying out gene delivery.Therefore,the application of water-soluble conjugated polymers in the field of gene delivery is gaining much promising perspective.So far,many water-soluble conjugated polymers have been reported to be widely used in the field of biopharmaceuticals,but water-soluble conjugated polymers which are applied to gene delivery and simultaneously image the process of gene delivery and intracellular localization have few reports.In this thesis,we designed three kinds of water-soluble conjugated polymers through changing the structures of the conjugated polymers backbone and the side chain group,then studied their photophysical properties.Its feasibility as a gene delivery vector was also explored.In addition,cell imaging applications of water-soluble conjugated polymers during gene delivery have also been investigated.This research work provides a new insight for the design of more excellent water-soluble conjugated polymers in the future to apply water-soluble conjugated polymers to cell imaging and gene delivery vectors.The specific research work includes the following contents:(1)Preparation of novel cationic water-soluble conjugated polythiophenes and their application in cell imaging and gene deliveryWe designed and synthesized a thiophene polymer monomer containing guanidinocarbonylpyrrole group in side chain.The fluorescent cationic conjugated polythiophene was synthesized by oxidative polymerization of anhydrous ferric chloride.The water-soluble cationic fluorescent polythiophene was obtained after the hydrophobic protective group was removed.Photophysical properties such as spectroscopy and emission spectroscopy were also tested.Then we verified the ability of the material to complex with plasmid DNA,and determined the minimum amount of material to be completely complexed with the plasmid DNA.Based on this amount,in vitro cell transfection and cell imaging experiments were then performed.(2)Preparation of novel cationic water-soluble conjugated poly(fluorene-co-phenylenes)and their application in cell imaging and gene deliveryWe designed and synthesized a functional dendritic quaternized side chain containing dibenzocyclooctene at the end of the group,and synthesized two kinds of fluorescent conjugated polymer backbones with side chain terminal azide by Suzuki coupling polymerization.We confirmed the structure of the synthesized fluorescent conjugated polymer backbone and determined its photophysical properties such as absorption and emission spectra.The functionalized side chain is covalently linked to the fluorescent polymer backbone by a “Copper-free Click reaction” to obtain a water-soluble fluorescent conjugated polymer,which was verified the ability of the material to complex with the plasmid DNA,and determined the minimum amount of material to be completely complexed with the plasmid DNA.On the basis of this amount,in vitro cell transfection and cell imaging experiments were performed.